A conventional IC socket assembly for a PGA (Pin Grid Array) package is disclosed in Japanese Unexamined Patent Publication No. 2002-313509 (FIG. 1, FIG. 11). This IC socket assembly comprises a base housing, which is constructed by molding plastic material over a metallic reinforcing plate having a square frame shape. In this PGA socket, a terminal mounting portion is positioned at the approximate center of the base housing. The metallic reinforcing plate reinforces the periphery of the terminal mounting portion. A cam driven sliding plate is provided on the base housing. An IC package is placed on the sliding plate. Lead pins of the IC package, engage with terminals, which are provided in the terminal mounting portion, by a horizontal sliding motion of the sliding plate, thereby establishing electrical connections between the lead pins and terminals.
In the conventional IC socket assembly described above, the terminals apply a force to the base housing during engagement of the lead pins and the terminals. This force works to deform the base housing. The base housing is reinforced by the square frame shaped metallic reinforcing plate to counter this force. However, the base housing is reinforced only at the periphery thereof. An opening is formed at the terminal mounting portion, where the terminals are provided. Thus the terminal mounting portion, to which force is applied by the terminals, is not reinforced. Accordingly, there is a possibility that deformation of the base housing will occur at the terminal mounting portion.
In another known IC socket assembly, a cover member presses, from above, on an IC package placed atop a socket housing to connect lead pins of the IC package to electrical contacts of the socket housing. In this IC Socket, the force from above is applied to the socket housing via the electrical contacts, and there is a possibility that the housing may be deformed and bend. Generally, IC sockets are mounted on printed circuit boards by soldering. However, excessive force is applied in a direction that acts to separate the socket housing from the circuit board at solder connections, particularly of the electrical contacts positioned at the peripheral portions, due to warping or bowing of the socket housing. In addition, the electrical contacts at the central portion separate from the IC package, and contact pressures as set by design cannot be obtained. Accordingly, it is difficult to realize highly reliable electrical connections in a state in which this force is applied.
However, the electrical contacts mounted in this type of IC socket assembly are arranged in a matrix. Therefore, it is difficult to prevent deformation of the socket housing by reinforcing the socket housing at a terminal mounting portion.